I think Trublion has started to make a little bubble nest in his bowl. It's just a little thing, not quite a gallon but little more than half a gallon.
My dad, as of today, has offered me money to get a bigger set up and heaters, since one of my fish is shredding his fins and I know the water is too cold for him. But Trublion seems quite happy in his little bowl. Originally I was going to move them both into new set ups, but if he seems happy/territorial in the one he's in, should I just leave him be?